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See detailDifferential item functioning among multiple groups: an outlier identification approach
Magis, David ULg

Scientific conference (2010, June 07)

Differential item functioning (DIF) has received increasing focus in the past decades. Recently, Magis and De Boeck (2010) proposed to identify differentially functioning items as outliers in a one ... [more ▼]

Differential item functioning (DIF) has received increasing focus in the past decades. Recently, Magis and De Boeck (2010) proposed to identify differentially functioning items as outliers in a one-dimensional space of DIF measures, using robust statistical tools for outlier identification. The purpose of this talk is to present an extension of this approach for the case of more than one focal group. In this multiple group framework, items can be characterized by multiple vectors of DIF measures, one for each focal group, so that a multivariate DIF space is obtained. DIF items can then be identified as outliers in this multivariate space, based on robust multivariate estimators of location and dispersion. The MCD (Minimum Covariance Determinant) estimator is shown to be adequate for this purpose. A major asset of the method that it can rely on existing DIF indices to define the DIF vectors, and that it does not need a purification step. Alternatively, it can be used to determine on an anchor set. The method will be illustrated by an example about calculator effects on mathematics test items. [less ▲]

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See detailDifferential item functioning in psychometrics: a state-of-the-art
Magis, David ULg

Scientific conference (2009, October)

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See detailDifferential location of nucleic acids within interchromatin granule clusters.
Thiry, Marc ULg

in European Journal of Cell Biology (1993), 62(2), 259-69

We have examined in great detail the distribution of nucleic acids within interchromatin granule clusters in different cell types by means of various immunocytochemical approaches. Using the in situ ... [more ▼]

We have examined in great detail the distribution of nucleic acids within interchromatin granule clusters in different cell types by means of various immunocytochemical approaches. Using the in situ polyadenylate nucleotidyl transferase-immunogold technique for RNA detection or anti-RNA antibodies, we decisively demonstrate the presence of appreciable amount of RNA in clusters of interchromatin granules of untreated cells. Neither the in situ terminal deoxynucleotidyl transferase-immunogold technique nor anti-DNA antibodies, nor the in situ nick-translation technique for DNA detection have revealed any DNA in the interchromatin granule clusters. However, dispersed chromatin sensitive to DNase I are found at the borders and in the close vicinity of interchromatin granule clusters. The results indicate that interchromatin granule clusters should not be nuclear structures directly involved in RNA transcription but rather in some other steps of RNA metabolism. [less ▲]

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See detailA differential Lyapunov framework for contraction analysis
Forni, Fulvio ULg; Sepulchre, Rodolphe ULg

in IEEE Transactions on Automatic Control (2014), 59(3), 614-628

Lyapunov's second theorem is an essential tool for stability analysis of differential equations. The paper provides an analog theorem for incremental stability analysis by lifting the Lyapunov function to ... [more ▼]

Lyapunov's second theorem is an essential tool for stability analysis of differential equations. The paper provides an analog theorem for incremental stability analysis by lifting the Lyapunov function to the tangent bundle. The Lyapunov function endows the state-space with a Finsler structure. Incremental stability is inferred from infinitesimal contraction of the Finsler metrics through integration along solutions curves. [less ▲]

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See detailDifferential membrane marker expression in adult rodent bone marrow mesenchymal and neural crest stem cells.
Wislet, Sabine ULg; Coste, Cécile ULg; Neirinckx, Virginie ULg et al

Poster (2015, March)

Bone marrow stem cells are endowed with in vitro multi-lineage differentiation abilities, and constitute an attractive autologous source of material for cell therapy. With regards to recent findings ... [more ▼]

Bone marrow stem cells are endowed with in vitro multi-lineage differentiation abilities, and constitute an attractive autologous source of material for cell therapy. With regards to recent findings, adult mesenchymal stem cells (MSC) are commonly assimilated to neural crest stem cells (NCSC), both isolated from adult bone marrow. The objective of this study was therefore to highlight significant differences for membrane markers between those two cell types. Using the minimal criteria for defining multipotent mesenchymal stromal cells as previously described by The International Society for Cellular Therapy, we were quite surprised that no significant difference could discriminate MSC from NCSC. To define new markers, we first performed a microarray comparison. Based on those results, we validated selected targets by RT-PCR, then by immunocytochemistry. In parallel, we observed that NCSC had the unique property (compared to MSC) to grow as spheres, which could also be used as a purification protocol for NCSC from adult bone marrow. Altogether, we demonstrated that P75NTR was the most significant discriminating marker between MSC and NCSC, isolated from mouse adult bone marrow, which could be used as selecting marker in an enrichment protocol. Sphere formation could then be used as a purification protocol for NCSC. [less ▲]

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See detailDifferential modulation of human chorionic gonadotropin secretion by epidermal growth factor in normal and malignant placental cultures.
Huot, R. I.; Foidart, Jean-Michel ULg; Nardone, R. M. et al

in Journal of Clinical Endocrinology and Metabolism (1981), 53(5), 1059-63

The ability of epidermal growth factor (EGF) to modulate the secretion of human chorionic gonadotropin (hCG) in both normal and malignant placental cells was compared. Receptors for EGF were present on ... [more ▼]

The ability of epidermal growth factor (EGF) to modulate the secretion of human chorionic gonadotropin (hCG) in both normal and malignant placental cells was compared. Receptors for EGF were present on the JAr line of choriocarcinoma cells and were localized to the trophoblast cells of normal placental organ cultures as detected by immunofluorescence. Despite the presence of EGF receptors, the normal placenta did not respond to EGF by significantly increasing its levels of hCG production. The JAr line of choriocarcinoma exhibited a 2-fold increase in hCG secretion after the addition of EGF. EGF stimulated growth in the JAr cells, as measured by the protein content of the cultures, but did not elevate the incorporation of [methyl-3H]thymidine in either the JAr cells or placental organ cultures. [less ▲]

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See detailDifferential operators acting on tensor densities
Mathonet, Pierre ULg

Doctoral thesis (1998)

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See detailDifferential pathomechanisms of epidermal necrolytic blistering diseases.
Paquet, Philippe ULg; Pierard, Gérald ULg

in International Journal of Molecular Medicine (2002), 10(6), 695-9

Staphylococcal scalded skin syndrome (SSSS) results from the effect of exfoliative-toxins produced by staphylococcal strains. The disease affects predominantly children, and is rare in adults. We report ... [more ▼]

Staphylococcal scalded skin syndrome (SSSS) results from the effect of exfoliative-toxins produced by staphylococcal strains. The disease affects predominantly children, and is rare in adults. We report two cases of the adult type of SSSS. Corticotherapy, chronic alcohol abuse and epilepsy-related immune changes might have been predisposing factors in these patients. The immunopathological characteristics of the inflammatory cell infiltrate in adults SSSS have not been thoroughly explored so far in the literature. Biopsies from 2 patients with bullous SSSS skin were studied by means of immunochemistry using a panel of 10 antibodies directed to FXIIIa, CD15, CD31, CD45R0, CD50, CD54, CD62E, CD95, CD106, and L1-protein, respectively. Cutaneous biopsies from related blistering diseases were compared. They included drug-induced toxic epidermal necrolysis (TEN), bullous impetigo and superficial pemphigus. A dense cell infiltrate composed of granulocytes (CD15+), macrophages (L1 protein+) and memory T cells (CD45R0+) and a strong expression of ICAM-3 (CD50) were present in the epidermis. CD95+ keratinocytes were lining the intraepidermal blisters. Type I dermal dendrocytes (Factor XIIIa+) were numerous and plump in the dermis. Bullous impetigo exhibited the same pattern of inflammatory cells, but with a lower density in type I dermal dendrocytes. TEN differed from SSSS by both the absence of CD15+ granulocytes and a stronger expression of the pro-apoptotic CD95 antigen in the epidermis. In superficial pemphigus, CD95 antigen was not expressed, and CD15+ granulocytes, CD45R0+ lymphocytes and L1 protein+ monocytes were much less numerous. It is concluded that the specific binding of SSSS-induced exotoxins to the desmosomes alters the keratinocyte metabolism leading to an inflammatory reaction followed by focal apoptosis. Our findings are in line with the concept that SSSS exotoxins might be superantigens. A common pathomechanism leading to epidermal destruction is likely operative in SSSS and bullous impetigo. The inflammatory cell composition in TEN and superficial pemphigus markedly differs from that in SSSS. [less ▲]

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See detailDifferential Performance between Two Timber Species in Forest Logging Gaps and in Plantations in Central Africa
Fayolle, Adeline ULg; Ouedraogo, Dakis-Yaoba ULg; Ligot, Gauthier ULg et al

in Forests (2015), 6(2), 380-394

To develop silvicultural guidelines for high-value timber species of Central African moist forests, we assessed the performance of the pioneer Milicia excelsa (iroko, Moraceae), and of the non-pioneer ... [more ▼]

To develop silvicultural guidelines for high-value timber species of Central African moist forests, we assessed the performance of the pioneer Milicia excelsa (iroko, Moraceae), and of the non-pioneer light demander Pericopsis elata (assamela, Fabaceae) in logging gaps and in plantations in highly degraded areas in south-eastern Cameroon. The survival and size of each seedling was regularly monitored in the silvicultural experiments. Differences in performance and allometry were tested between species in logging gaps and in plantations. The two species performance in logging gaps was significantly different from plantations and concurred with the expectations of the performance trade-off hypothesis but not with the expectations of species light requirements. The pioneer M. excelsa survived significantly better in logging gaps while the non-pioneer P. elata grew significantly faster in plantations. The high mortality and slow growth of M. excelsa in plantations is surprising for a pioneer species but could be explained by herbivory (attacks from a gall-making psyllid). Identifying high-value native timber species (i) with good performance in plantations such as P. elata is of importance to restore degraded areas; and (ii) with good performance in logging gaps such as M. excelsa is of importance to maintain timber resources and biodiversity in production forests. [less ▲]

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See detailDifferential PIXE measurements for the stratigraphic analysis of the painting Madonna dei Fusi by Leonardo da Vinci
Grassi, Novella; Migliori, Alessandro; Mandò, PierAndrea et al

in X-Ray Spectrometry [=XRS] (2005), 34(4), 306-309

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See detailDifferential population studies using asteroseismology: Solar-like oscillating giants in CoRoT fields LRc01 and LRa01
Miglio, A.; Chiappini, C.; Morel, Thierry ULg et al

in European Physical Journal Web of Conferences (2013, March 01)

Solar-like oscillating giants observed by the space-borne satellites CoRoT and Kepler can be used as key tracers of stellar populations in the Milky Way. When combined with additional photometric ... [more ▼]

Solar-like oscillating giants observed by the space-borne satellites CoRoT and Kepler can be used as key tracers of stellar populations in the Milky Way. When combined with additional photometric/spectroscopic constraints, the pulsation spectra of solar-like oscillating giant stars not only reveal their radii, and hence distances, but also provide well-constrained estimates of their masses, which can be used as proxies for the ages of these evolved stars. In this contribution we provide supplementary material to the comparison we presented in Miglio et al. (2013) between populations of giants observed by CoRoT in the fields designated LRc01 and LRa01. [less ▲]

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See detailDifferential production of cytokines and activation of NF-kappa B in HPV-transformed keratinocytes
Havard, L.; Delvenne, Philippe ULg; Frare, P. et al

in Virology (2002), 298(2), 271-285

We have proposed that chronic infection of keratinocytes by HPV modifies the expression of potentially important cytokines by interfering with the NF-kappaB signal pathway We evaluated the constitutive ... [more ▼]

We have proposed that chronic infection of keratinocytes by HPV modifies the expression of potentially important cytokines by interfering with the NF-kappaB signal pathway We evaluated the constitutive and IL-1beta-induced expression of GM-CSF and TNF-alpha and the expression/activity of NF-kappaB in HPV+ and HPV- cell lines. Despite the enhanced expression of the functional components of the NF-kappaB signaling pathway in HPV+ cell lines by a mechanism implicating the HPV oncoprotein E6, the constitutive activity of NF-kappaB and the expression of GM-CSF/TNF-alpha were significantly reduced relative to the HPV- cell line and normal keratinocytes. In contrast, we observed a superactivation of NF-kappaB activity after IL-1beta stimulation, a strong and transient induction of GM-CSF/TNF-alpha mRNA, but undetectable levels of secreted proteins in HPV+ cell lines. Our data demonstrate that E6 modulates the NF-kappaB signaling pathway and suggest that other HPV proteins also interfere with GM-CSF/TNF-alpha expression by transcriptional and/or posttranscriptional mechanisms. (C) 2002 Elsevier Science (USA). [less ▲]

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See detailDifferential proteomic analysis of a human breast tumor and its matched bone metastasis identifies cell membrane and extracellular proteins associated with bone metastasis
Dumont, Bruno ULg; Castronovo, Vincenzo ULg; Peulen, Olivier ULg et al

in Journal of Proteome Research (2012)

The classical fate of metastasizing breast cancer cells is to seed and form secondary colonies in bones. The molecules closely associated with these processes are predominantly present at the cell surface ... [more ▼]

The classical fate of metastasizing breast cancer cells is to seed and form secondary colonies in bones. The molecules closely associated with these processes are predominantly present at the cell surface and in the extracellular space, establishing the first contacts with the target tissue. In this study, we had the rare opportunity to analyze a bone metastatic lesion and its corresponding breast primary tumor obtained simultaneously from the same patient. Using mass spectrometry, we undertook a proteomic study on cell surface and extracellular protein-enriched material. We provide a repertoire of significantly modulated proteins, some with yet unknown roles in the bone metastatic process as well as proteins notably involved in cancer cell invasiveness and in bone metabolism. The comparison of these clinical data with those previously obtained using a human osteotropic breast cancer cell line highlighted an overlapping group of proteins. Certain differentially expressed proteins are validated in the present study using immunohistochemistry on a retrospective collection of breast tumors and matched bone metastases. Our exclusive set of selected proteins supports the set-up of further investigations on both clinical samples and experimental bone metastasis models that will help to reveal the finely coordinated expression of proteins that favor the development of metastases in the bone microenvironment. [less ▲]

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See detailDifferential Regulation of Chondrocyte Metabolism by Oncostatin M and Interleukin-6
Sanchez, Christelle ULg; Deberg, Michelle ULg; Devel, Philippe et al

in Osteoarthritis and Cartilage (2004), 12(10), 801-10

OBJECTIVE: To determine the effects of interleukin (IL)-6 and oncostatin M (OSM) added separately or in combination with IL-1beta on human osteoarthritic (OA) chondrocytes in alginate beads. DESIGN: Human ... [more ▼]

OBJECTIVE: To determine the effects of interleukin (IL)-6 and oncostatin M (OSM) added separately or in combination with IL-1beta on human osteoarthritic (OA) chondrocytes in alginate beads. DESIGN: Human chondrocytes were isolated from OA cartilage and cultured in alginate beads for 12 days, in the absence or in the presence of increasing amounts of IL-6 (20-500ng/ml) with its soluble receptor or OSM (0.1-10ng/ml) and with or without IL-1beta (1.7ng/ml). Aggrecan (AGG), transforming growth factor-beta1 (TGF-beta1), stromelysin-1 [matrix metalloprotease (MMP)-3], tissue inhibitor of metalloproteinases-1 (TIMP-1), macrophage inflammatory protein-1 beta (MIP-1beta), IL-6 and IL-8 productions were assayed by specific enzyme amplified sensitivity immunoassays. Prostaglandin (PG)E(2) was measured by a specific radioimmunoassay and nitrite (NO(2)(-)) by a spectrophotometric method based upon the Griess reaction. RESULTS: OSM, but not IL-6, decreased basal AGG and TGF-beta1 synthesis. Although IL-6 stimulated basal TIMP-1 production, it did not significantly modify MMP-3/TIMP-1 ratio. In contrast, 10ng/ml OSM highly increased TIMP-1 production, and decreased by half the ratio MMP-3/TIMP-1. IL-1beta highly stimulated *NO, IL-8, IL-6, MIP-1beta and PGE(2) synthesis but decreased AGG and TGF-beta1 production. Neither IL-6 nor OSM modulated IL-1beta-inhibitory effect on AGG production. IL-6, but not OSM, reversed IL-1beta-induced TGF-beta1 inhibition. At 1-10ng/ml, OSM significantly decreased IL-1beta-stimulated IL-8, MIP-1beta, PGE(2) and *NO production but amplified IL-1beta stimulating effect on IL-6 production. IL-6 had no effect on these parameters. CONCLUSIONS: OSM and IL-6, two glycoprotein 130 binding cytokines, show different activity profiles on OA chondrocytes, indicating that these cytokines could play different roles in the OA disease process. [less ▲]

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See detailDifferential regulation of the REGγ–proteasome pathway by p53/TGF-β signalling and mutant p53 in cancer cells
Ali, Amjad ULg; Wang, Zhuo; Fu, Junjiang et al

in Nature Communications (2013)

Proteasome activity is frequently enhanced in cancer to accelerate metastasis and tumorigenesis. REGγ, a proteasome activator known to promote p53/p21/p16 degradation, is often overexpressed in cancer ... [more ▼]

Proteasome activity is frequently enhanced in cancer to accelerate metastasis and tumorigenesis. REGγ, a proteasome activator known to promote p53/p21/p16 degradation, is often overexpressed in cancer cells. Here we show that p53/TGF-β signalling inhibits the REGγ–20S proteasome pathway by repressing REGγ expression. Smad3 and p53 interact on the REGγ promoter via the p53RE/SBE region. Conversely, mutant p53 binds to the REGγ promoter and recruits p300. Importantly, mutant p53 prevents Smad3/N-CoR complex formation on the REGγ promoter, which enhances the activity of the REGγ–20S proteasome pathway and contributes to mutant p53 gain of function. Depletion of REGγ alters the cellular response to p53/TGF-β signalling in drug resistance, proliferation, cell cycle progression and proteasome activity. Moreover, p53 mutations show a positive correlation with REGγ expression in cancer samples. These findings suggest that targeting REGγ–20S proteasome for cancer therapy may be applicable to human tumours with abnormal p53/Smad protein status. Furthermore, this study demonstrates a link between p53/TGF-β signalling and the REGγ–20S proteasome pathway, and provides insight into the REGγ/p53 feedback loop. [less ▲]

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See detailDifferential regulation of the REGγ–proteasome pathway by p53/TGF-β signalling and mutant p53 in cancer cells
Ali, Amjad ULg; wang, zhou; Fu, Junjiang et al

in Nature Communications (2013), 1(4), 1-16

Proteasome activity is frequently enhanced in cancer to accelerate metastasis and tumorigenesis. REGγ, a proteasome activator known to promote p53/p21/p16 degradation, is often overexpressed in cancer ... [more ▼]

Proteasome activity is frequently enhanced in cancer to accelerate metastasis and tumorigenesis. REGγ, a proteasome activator known to promote p53/p21/p16 degradation, is often overexpressed in cancer cells. Here we show that p53/TGF-β signalling inhibits the REGγ–20S proteasome pathway by repressing REGγ expression. Smad3 and p53 interact on the REGγ promoter via the p53RE/SBE region. Conversely, mutant p53 binds to the REGγ promoter and recruits p300. Importantly, mutant p53 prevents Smad3/N-CoR complex formation on the REGγ promoter, which enhances the activity of the REGγ–20S proteasome pathway and contributes to mutant p53 gain of function. Depletion of REGγ alters the cellular response to p53/TGF-β signalling in drug resistance, proliferation, cell cycle progression and proteasome activity. Moreover, p53 mutations show a positive correlation with REGγ expression in cancer samples. These findings suggest that targeting REGγ–20S proteasome for cancer therapy may be applicable to human tumours with abnormal p53/Smad protein status. Furthermore, this study demonstrates a link between p53/TGF-β signalling and the REGγ–20S proteasome pathway, and provides insight into the REGγ/p53 feedback loop. [less ▲]

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See detailDifferential regulation of wild-type and mutant alpha-synuclein binding to synaptic membranes by cytosolic factors.
Wislet-Gendebien, Sabine ULg; Visanji, Naomi P; Whitehead, Shawn N et al

in BMC Neuroscience (2008), 9

BACKGROUND: Alpha-Synuclein (alpha-syn), a 140 amino acid protein associated with presynaptic membranes in brain, is a major constituent of Lewy bodies in Parkinson's disease (PD). Three missense ... [more ▼]

BACKGROUND: Alpha-Synuclein (alpha-syn), a 140 amino acid protein associated with presynaptic membranes in brain, is a major constituent of Lewy bodies in Parkinson's disease (PD). Three missense mutations (A30P, A53T and E46K) in the alpha-syn gene are associated with rare autosomal dominant forms of familial PD. However, the regulation of alpha-syn's cellular localization in neurons and the effects of the PD-linked mutations are poorly understood. RESULTS: In the present study, we analysed the ability of cytosolic factors to regulate alpha-syn binding to synaptic membranes. We show that co-incubation with brain cytosol significantly increases the membrane binding of normal and PD-linked mutant alpha-syn. To characterize cytosolic factor(s) that modulate alpha-syn binding properties, we investigated the ability of proteins, lipids, ATP and calcium to modulate alpha-syn membrane interactions. We report that lipids and ATP are two of the principal cytosolic components that modulate Wt and A53T alpha-syn binding to the synaptic membrane. We further show that 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine (C16:0 PAF) is one of the principal lipids found in complex with cytosolic proteins and is required to enhance alpha-syn interaction with synaptic membrane. In addition, the impaired membrane binding observed for A30P alpha-syn was significantly mitigated by the presence of protease-sensitive factors in brain cytosol. CONCLUSION: These findings suggest that endogenous brain cytosolic factors regulate Wt and mutant alpha-syn membrane binding, and could represent potential targets to influence alpha-syn solubility in brain. [less ▲]

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